There is a waveform estimation device that receives an input of an actual measurement data including regular waveform components and irregular waveform components, estimates the regular waveform components serving as a trend of the actual measurement data, and calculates a difference between the actual measurement data and the regular waveform components, thereby estimating the irregular waveform components.
Such a waveform estimation device can identify the regular waveform components and the irregular waveform components included in the actual measurement data.
For example, in a case where the actual measurement data is a signal including regular long-period waveform components caused by tide (hereinafter, referred to as “tidal components”), and irregular short-period waveform components caused by tsunami (hereinafter, referred to as “tsunami components”), by predicting the regular tidal components serving as a trend of the actual measurement data, and obtaining a difference between the predicted value and the actual measurement data, the irregular tsunami components can be extracted.
In the detection processing of tsunami, if the extracted tsunami components are larger than a preset threshold value, it is determined that the actual measurement data shows the existence of tsunami.
Here, regular tidal components can be predicted from an astronomical tide level, and the astronomical tide level is a predicted value of a tide level that is calculated by analyzing tide level data observed in the past.
However, while the astronomical tide level can be calculated in a tide gauge station provided in a predetermined standard port, it cannot be calculated at a point where a tide gauge station is not provided.
Thus, in the waveform estimation device disclosed in the following Patent Literature 1, by identifying components having a period equal to or larger than a threshold value as a change in water level that is caused by tide, tidal components related to a change in water level that is caused by tide are extracted from actual measurement data.
The extraction of tidal components is realized by performing Fourier transformation-based filtering processing using a certain period serving as a threshold value as a numerical filter.
Tsunami can be thereby detected even at a point where a tide gauge station is not provided.